1. Field of the Invention
The present invention relates to electric equipments such as an electronic cash register or to a key device used for a traveling bag.
2. Description of the Related Art
A cashier having a cashier code assigned to an electronic cash register, for example, can be registered in this cash register and can operate it. A keyboard is used as an input means for inputting the cashier code. There are two methods of inputting a cashier code. First, after an input of a cashier code is declared by a declarative key, the code is entered by numerical keys (this method may be reversible), and second, a preset key in which a cashier code is preset is used. In the first method, a cashier code input is cumbersome, and if an erroneous code is input and has already been registered, the input code is valid, and an erroneous operation is performed. On the other hand, although the second method has good operability, since the number of preset keys is limited, the number of cashier codes which can be preset is very small. Therefore, in recent years, an electronic cash register using an electromagnetic key switch as a means for inputting a cashier code has been used.
FIG. 1 is a view showing an arrangement of a main part of a conventional electromagnetic key switch of this type, as is disclosed in Published Unexamined Japanese Patent Application No. 62-73513. In FIG. 1, a key 1 comprises a plate-like key main body 1a consisting of a magnetically permeable material and a head portion 1b integrally formed at one end of the key main body 1a. Reference numeral 2 denotes a key insertion hole in which the key main body 1a is inserted. Four Hall elements 3a, 3b, 3c, and 3d are linearly arranged along the insertion direction of the key main body 1a on a plate member 6 constituting the side portion of the key insertion hole 2.
Magnet buried portions 4a, 4b, 4c, and 4d are formed in the key main body 1a such that the portions 4a, 4b, 4c, and 4d are arranged at positions respectively opposite to the Hall elements 3a to 3d when the key main body 1a is normally inserted into the key insertion hole 2. Magnets 5 are selectively buried in the magnet buried portions 4a to 4d.
The magnets 5 are buried in the magnet buried portions 4a and 4d of the magnet buried portions 4a to 4d but not buried in the magnet buried portions 4b and 4c. In this case, output signals a and b from the elements 3a and 3d of the Hall elements 3a to 3d are turned on by the magnetic forces of the magnets 5, and output signals b and c from the elements 3b and 3c are kept set in an OFF state.
As shown in FIG. 2, the output signals a, b, and c from the Hall elements 3a, 3b, and 3c are input to input terminal A0, Al, and A2 of a buffer IC 6, respectively, and the output signal d from the Hall element 3d is input to a power supply terminal Vcc of the buffer IC 6. Output terminals YO, Y1, and Y2 respectively corresponding to the input terminals A0, Al, and A2 of the buffer IC 6 are connected to a microprocessor I/O port 7 constituting the control main body of the electronic cash register. That is, the output signal d from the Hall element 3d serves as a drive power supply of the buffer IC 6, and the output signals a to c from the Hall elements 3a to 3c are fetched by the buffer IC 6 in response to an ON state of the output signal d from the Hall element 3d, such that the output signals a to c are loaded in a microprocessor (not shown) of the electronic cash register through the I/O port 7.
In all keys, the magnets 5 are always buried in the corresponding magnet buried portions 4d located at positions opposite to the Hall elements 3d in the key main bodies 1a, and the magnets 5 are selectively buried in the magnet buried portions 4a to 4c, thereby setting different types of keys. For this reason, every time when different types of keys are required according to different application purposes, the step of burying magnets in pre-selected buried portions must be performed. Therefore, different types of keys cannot be easily manufactured. In addition, since an electromagnet is used, a low-profile key cannot be easily obtained.